This invention relates to a method and apparatus for manufacturing a prepreg lamination by laminating prepregs. More particularly, a method and apparatus for laminating a prepreg of the first layer of the lamination on the surface.
Composite materials have been abundantly used for manufacturing parts of aircrafts, parts of mechanical structural members, and sports and leisure articles. As the composite material, is generally used a prepreg lamination which is prepared by impregnating epoxy resin or the like into such reinforcing fibers as glass fibers, carbon fibers, boron fibers or the like to form a prepreg sheet, laminating the prepreg sheets into a prepreg laminated sheet and cutting the prepreg laminated sheet to have a configuration suitable for the products. After subjecting the prepreg laminated sheet to bonding or the like working the prepreg laminated sheet is applied with pressure and heat in vacuum or reduced pressure atmosphere to obtain an article made of composite material. The lamination methods are classified into one in which the lamination is made by a manual operation and the other in which the lamination is made by an automatic machine. However in both methods the lamination methods are substantially the same.
The method of lamination by manual operation will be described with reference to FIGS. 5(a) through 5(f). Usually one side of a prepreg sheet 1 is bonded with a carrier sheet 2 impregnated with a silicone resin, and a prepreg tape 3 made up of the carrier sheet 2 and the prepreg sheet 1 is wound about a core pipe 4a (see FIG. 5(a)) to form a prepreg roll 4. Then a prepreg tape 3 is payed out from the prepreg roll 4 and cut to have a predetermined dimension and configuration. Then the carrier sheet 2 is peeled off from the prepreg tape 3 (see FIG. 5(c)) and the prepreg sheet 1 from which the carrier sheet 2 has been removed is bonded with a face sheet 5 used as a substratum for lamination, made of a plastic sheet and to be peeled off later. Then on the prepreg sheet 1, a predetermined number of prepreg sheets are laminated with their orientations of fibers changed, for example 45.degree., 90.degree. (see FIG. 5(d)) for laminating prepreg sheets on the face sheet 5. Then only the prepreg laminated sheet is cut to have a predetermined configuration without cutting the face sheet 5. Then the face sheet 5 is peeled off from the prepreg laminated sheet to form a prepreg laminated member 6 (see FIG. 5(e)). Then the prepreg laminated member 6 is bent and applied with pressure and heat in vacuum or in a reduced pressure atmosphere to form a molded member 7 as shown in FIG. 5(f).
Since in the first layer obtained by bonding the prepreg sheet 1 to the face sheet 5, by taking into consideration the fact that the face sheet 5 is peeled off in the subsequent step, a plastic sheet easy to peel off is used, and as the adhesive force is low, there is a tendency of entrapping air bubbles 8 between the prepreg sheet and the plastic sheet when the prepreg sheets are laminated under these conditions, undesirable phenomena of the first layer of the prepreg sheet 1 affect the subsequent lamination operation, thereby decreasing the quality of the prepreg laminated member 6. As a consequence, where these defects are corrected by a manual operation, the surface of the prepreg sheet is pressed by hands or a roller for purging out the air bubbles from the prepreg sheets 1 while observing the operation with the eyes of the operator for removing wrinkles. Since these operations are repeated, large labour and time are necessary. Where the face sheet 5 and the prepreg sheet are laminated by an automatic machine, the most adequate values are utilized by varying the pressure of the prepreg tape 3 applied to the face sheet and the tension and laminating speed of the prepreg tape 3. These methods also accompany the phenomena of air bubbles, wrinkles and peel off. Unless the first layer is perfectly corrected, subsequent laminating operations are affected so that the correction by manual operations are essential, thereby greatly decreasing the operating efficiency.